Sanitary napkins have customarily included a central absorbent element having a body facing side, a garment facing side, longitudinally extending sides and transverse ends. In the past, these products sometimes failed to provide proper protection because the edges of the crotch of the panty, to which these products are adhered, tended to enfold onto the body facing side of the napkin. This condition can cause the panty to be stained with body fluid, either emanating from the napkin or exuding from the body of the wearer.
In order to overcome this deficiency, several of the more recent napkin designs have included flaps extending along the longitudinal sides of the absorbent element. Mattingly, U.S. Pat. No. 4,608,047, for example, is directed to such a sanitary napkin having flaps extending from a central absorbent. This product is adhesively attached to an inner crotch portion of a users' undergarment and its side flaps are then folded onto an outer surface of the crotch portion to protect the garment. McNair, U.S. Pat. No. 4,285,343, is also directed to a napkin having flaps for folding over the outer surface of the wearer's undergarment. Both of these patents provide for embodiments that include absorbent pads in their flaps, thereby inviting the transmission of body fluid from the central absorbent element into the flaps.
Von Tilberg, U.S. Pat. No. 4,589,876, is directed to a sanitary napkin that includes a central absorbent pad and two flaps extending laterally from the pad. This napkin design preferentially bends at a line of juncture between each flap and the longitudinal edges of the central absorbent pad. The flaps of this napkin comprise a liquid pervious top sheet, a liquid impervious back sheet and an absorbent core interposed between the top sheet and back sheet. Additionally, each flap has a flexible axis located in the body of the flap which allows the flap to be folded onto itself to form a gasket-like seal between the body of the user and the flaps along the flexible axis in the body of the flaps. This patent requires the use of "good body contact" to provide a barrier to lateral flow of menstrual fluid from the crotch area.
It is understood that when fluid comes in contact with the pulp of the central absorbent, it is readily absorbed by a series of large capillaries in the pulp structure. This fluid travels through the molded pulp of these napkins and meets the often used bottom tissue which has very small capillaries. When fluid reaches these fine capillaries it travels at a faster rate and spreads through the tissue into the flaps. The molded pulp and the tissue consequently become one absorbent system. One major drawback of this system is that the absorbent tissue in the flaps may draw body fluid away from the central absorbent element and out of the inner crotch portion of the undergarment, creating a potential for staining the garments of the wearer.
Although not directed to napkins with flaps. some prior art products teach the use of sealing means in their central absorbent.
Whitehead, U.S. Pat. No. 4,526,825, is directed to a sanitary appliance having a fused barrier for sealing fluid run off and wicking migration. The barrier of this patent is created by fusing the fluid permeable wrap around the periphery of the central absorbent. This napkin does not provide flaps for protecting the undergarment, nor does it appreciate the value of compartmentalized absorbency.
Black, U.S. Pat. No. 4,200,103 discloses a napkin design having at least two fluid barrier seal lines extending longitudinally with the product and sealing the longitudinal edge portion of the napkin's barrier sheet to the cover portion. This napkin is not concerned with the transmission of body fluid out of the crotch portion through laterally extending flaps. This patent also does not teach absorbent material located outside the central pad area for protection against body fluid which may run off the surface of the pad and along the body.
Ahr, U.S. Pat. No. 4,321,924, and Csillag, U.S. Pat. No. 4,015,604, disclose fluid barriers within or along the perimeter of their central absorbent elements and supplemental absorbent areas outside of the central absorbent. Csillag refers to the supplemental absorbent areas as margins that provide a comfortable interface between the hydrophobic zones of the central absorbent when the product is worn. Csillag warns that the zones should not be so wide as to substantially detract from the body fluid absorbing capacity of the product as a whole, thus indicating that the zones are designed for comfort rather than absorbency. Ahr states that his border provides added protection against undergarment soiling from discharged fluids which flow across the top sheet and beyond the absorbent core. These patents, however, fail to disclose absorbent wing members that may be folded around the outer portion of an undergarment for protecting the panty against soiling. Furthermore, these designs are not concerned with the problems associated with absorbing flaps and the transmission of body fluid through the napkin and out of the inner crotch portion of the undergarment.
Accordingly, there is still a need for a winged sanitary napkin that provides a barrier for preventing fluid transfer via tissue wicking from the central absorbent element to the flaps. There is also a need for a sanitary napkin that provides for compartmentalized absorbency of its flaps as a reserve to be used in exceptional circumstances.